diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.def b/llvm/include/llvm/IR/RuntimeLibcalls.def
--- a/llvm/include/llvm/IR/RuntimeLibcalls.def
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.def
@@ -286,6 +286,7 @@
 HANDLE_LIBCALL(FPEXT_F80_F128, "__extendxftf2")
 HANDLE_LIBCALL(FPEXT_F64_F128, "__extenddftf2")
 HANDLE_LIBCALL(FPEXT_F32_F128, "__extendsftf2")
+HANDLE_LIBCALL(FPEXT_F16_F128, "__extendhftf2")
 HANDLE_LIBCALL(FPEXT_F32_F64, "__extendsfdf2")
 HANDLE_LIBCALL(FPEXT_F16_F32, "__gnu_h2f_ieee")
 HANDLE_LIBCALL(FPROUND_F32_F16, "__gnu_f2h_ieee")
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -224,6 +224,8 @@
   if (OpVT == MVT::f16) {
     if (RetVT == MVT::f32)
       return FPEXT_F16_F32;
+    if (RetVT == MVT::f128)
+      return FPEXT_F16_F128;
   } else if (OpVT == MVT::f32) {
     if (RetVT == MVT::f64)
       return FPEXT_F32_F64;
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -417,8 +417,10 @@
   setOperationAction(ISD::STRICT_UINT_TO_FP, MVT::i32, Custom);
   setOperationAction(ISD::STRICT_UINT_TO_FP, MVT::i64, Custom);
   setOperationAction(ISD::STRICT_UINT_TO_FP, MVT::i128, Custom);
+  setOperationAction(ISD::FP_ROUND, MVT::f16, Custom);
   setOperationAction(ISD::FP_ROUND, MVT::f32, Custom);
   setOperationAction(ISD::FP_ROUND, MVT::f64, Custom);
+  setOperationAction(ISD::STRICT_FP_ROUND, MVT::f16, Custom);
   setOperationAction(ISD::STRICT_FP_ROUND, MVT::f32, Custom);
   setOperationAction(ISD::STRICT_FP_ROUND, MVT::f64, Custom);
 
diff --git a/llvm/test/CodeGen/AArch64/arm64-fp128.ll b/llvm/test/CodeGen/AArch64/arm64-fp128.ll
--- a/llvm/test/CodeGen/AArch64/arm64-fp128.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-fp128.ll
@@ -219,6 +219,7 @@
 ; CHECK: ret
 }
 
+@varhalf = global half 0.0, align 2
 @varfloat = global float 0.0, align 4
 @vardouble = global double 0.0, align 8
 
@@ -227,6 +228,12 @@
 
   %val = load fp128, fp128* @lhs, align 16
 
+  %half = fptrunc fp128 %val to half
+  store half %half, half* @varhalf, align 2
+; CHECK: ldr q0, [{{x[0-9]+}}, :lo12:lhs]
+; CHECK: bl __trunctfhf2
+; CHECK: str h0, [{{x[0-9]+}}, :lo12:varhalf]
+
   %float = fptrunc fp128 %val to float
   store float %float, float* @varfloat, align 4
 ; CHECK: bl __trunctfsf2
@@ -245,6 +252,13 @@
 
   %val = load fp128, fp128* @lhs, align 16
 
+  %half = load half, half* @varhalf
+  %fromhalf = fpext half %half to fp128
+  store volatile fp128 %fromhalf, fp128* @lhs, align 16
+; CHECK: ldr h0, [{{x[0-9]+}}, :lo12:varhalf]
+; CHECK: bl __extendhftf2
+; CHECK: str q0, [{{x[0-9]+}}, :lo12:lhs]
+
   %float = load float, float* @varfloat
   %fromfloat = fpext float %float to fp128
   store volatile fp128 %fromfloat, fp128* @lhs, align 16